New polyester polyols and their use as polyol component in two-component polyurethane lacquers

Abstract

The present invention is directed to polyester polyols in the hydroxyl number range of about 80 to 250 which are based on reaction products of (a) about 52 to 60 mole % of a polyol component with (b) about 40 to 48 mole % of dicarboxylic acid component, characterized in that (a) the polyol component is based on (i) about 2 to 30 mole % of at least one dihydric aliphatic alcohol which has at least two carbon atoms and is different from neopentyl glycol, (ii) about 5 to 40 mole % of at least one aliphatic alcohol which is at least trihydric and has at least 3 carbon atoms, (iii) about 20 to 60 mole % of bis-(hydroxymethyl)-cyclohexane and (iv) about 10 to 50 mole % of neopentyl glycol, and (b) the dicarboxylic acid component is based on (v) about 50 to 99 mole % of at least one aliphatic, saturated dicarboxylic acid or an anhydride of such an acid containing at least 2 carbon atoms and (vi) about 0.5 to 50 mole % of at least one aliphatic unsaturated dicarboxylic acid or its anhydride having at least 4 carbon atoms, the percentages under (a) and (b) adding up to 100. The present invention is also directed to the use of these polyester polyols as a binder component for two-component polyurethane lacquers containing lacquer polyisocyanates for the production of lacquer coats on molded plastic parts.

What is claimed is: 
     
       1. A polyester polyol having a hydroxyl number of about 80 to 250 and comprising the reaction product of (a) about 52 to 60 mole % of a polyol component comprising (i) about to 2 to 30 mole % of at least one dihydric aliphatic alcohol other than neopentyl glycol which has at least two carbon atoms,   (ii) about 5 to 40 mole % of at least one aliphatic alcohol which has three or more hydroxyl groups and at least three carbon atoms,   (iii) about 20 to 60 mole % of bis-(hydroxymethyl)-cyclohexane and   (iv) about 10 to 50 mole % of neopentyl glycol and     (b) about 40 to 48 mole % of a dicarboxylic acid component comprising (v) about 50 to 99 mole % of at least one aliphatic, saturated dicarboxylic acid or anhydride of such acid containing at least two carbon atoms and   (vi) about 0.5 to 50 mole % of at least one aliphatic, unsaturated dicarboxylic acid or an anhydride of such an acid containing at least four carbon atoms, the percentages given under (a) and (b) adding up to 100.       
     
     
       2. The polyester polyol of claim 1 wherein component (i) comprises hexane-1,6-diol, component (ii) comprises trimethylolpropane, glycerol, pentaerythritol or mixtures thereof and component (iii) comprises 1,4-bis-(hydroxymethyl)-cyclohexane. 
     
     
       3. The polyester polyol of claim 1 wherein component (v) comprises adipic acid and component (vi) comprises maleic acid, maleic acid anhydride or mixtures thereof. 
     
     
       4. The polyester polyol of claim 2 wherein component (v) comprises adipic acid and component (vi) comprises maleic acid, maleic acid anhydride or mixtures thereof. 
     
     
       5. A two-component polyurethane lacquer for coating flexible substrates which comprises a polyisocyanate component and a polyol component comprising the polyester polyol of claim 1.